The hinge in Unio tumidus Retzius, 1778 (Bivalvia: Unionidae) may reflect anthropogenic development in the waterbody catchment

This study is a first attempt to estimate the impact of development in the catchment areas of rivers and lakes on the variability of hinge morphology in Unio tumidus Retzius, 1778, one of the most common species of freshwater bivalves in Europe. A preliminary examination of conchological materials reveals that individuals of U. tumidus present variations (morphs) of this character. The shells of U. tumidus were collected from northwestern European Russia, from 6 lakes of various trophic status and 4 rivers. The samples show a relationship of morph frequencies with the anthropogenic development of the catchment area. This relationship is reflected in 2 indices: the overall level of intrapopulation diversity and the proportion of individuals deviating from the most common pattern. Both indices increase with an increasing level of development in the catchment. The results of this study show the possibility of practical use of hinge morphology in monitoring waterbodies.